Xbox Music for the Xbox 360, Windows tablets, and phones was unveiled by Microsoft today in a short preview at E3.

With the Zune music brand being de-emphasized, the Xbox Music service seems poised to take center stage in Microsoft's music ambitions with its 30 million tracks, compared to 11 million in the Zune Music Marketplace. Microsoft promised Xbox Music for the Xbox 360, Windows Phone, and Windows 8, but Gartner analyst Michael Gartenberg reports that the service will also run on iOS and Android. Support for anything other than Microsoft platforms was not announced publicly by Microsoft, however.

Xbox Music will be the "music service we have always dreamed of building," with great ways to share and discover new music, Microsoft marketing and strategy executive Yusuf Mehdi said at the E3 conference today.

Xbox Music will provide "access to your music collection from any screen, combined with unique social features," Microsoft said in marketing materials accompanying the announcement. "Xbox Music includes a music store for song downloads, music subscription offering, artist-based radio, and a great cross-screen client for your personal music collections."

While details on the music service (including an availability date) were scarce, Microsoft also announced several dozen new entertainment deals that will bring more video content to Xbox 360 owners. Content coming later this year includes NHL GameCenter Live, NBA Game Time, NBA League Pass, and 24/7 programming from several ESPN channels.

Over the next 12 months, an additional 30 or so content partners will arrive on Xbox, with many of them launching in just one or two countries. The US will get Comedy Central Stand Up, GameSpot TV, Nickelodeon, Paramount Movies, Rhapsody, Slacker Radio, The Weather Channel, and more (full list is here.)

The music and video deals will help cement the Xbox 360's position as a home media center that goes far beyond the capabilities of traditional video game consoles. With the "SmartGlass" technology also announced today, you can likely expect lots of cross-device scenarios, such as using your phone or tablet to control the music and video playing on an Xbox 360-powered television.